Shakun Redux: Master tricksed us! I told you he was tricksy!

Watts Up With That? ^ | April 7, 2012 | Willis Eschenbach

[Rocky]

The quote above is from Lord of the Rings, an exchange between Gollum and Smeagol, and it encapsulates my latest results from looking into the Shakun 2012 paper, “Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation” (paywalled, at Nature hereinafter Shakun2012). I discussed the paper in my post “Dr. Munchausen Explains Science By Proxy“. Please see that post for the underlying concepts and citations.

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There was excellent agreement between the Shakun2012 data and the ice core records I had downloaded … but there was also a surprise.

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-the big surprise was not what the ice core records showed. It was what the Shakun2012 authors didn’t show.

I’m sure you can see just what those bad-boy scientists have done. Look how they have cut the modern end of the ice core CO2 record short, right at the time when CO2 started to rise again …

[Rocky]

Shakun, et al, did not present the whole story. CO2 has apparently been rising for 7,000-8,000 years.

[Richard from IL]

If the data doesn’t support the theory, hide the data.

[SunTzuWu]

That's because CO2 levels trail temp changes. Warming causes CO2 rise not the other way around. It's called a trailing proxy. CO2 levels have been rising for the last 7K - 8K years because the Earth was coming out of the last ice age.

[agere_contra]

As a commentator pointed out: the Younger Dryas Stadial (a sharp ‘kink’ in temperature that happened some 10,000 years BC, or 12,000 BP) is clearly visible in the data.

The YDS is thought to have occurred as the North American Ice Sheets collapsed, causing a sharp reversal in the general warming trend after the end of the Ice Age 20,000 BP.

In essence the temperature goes up, then down, then up. The CO2 follows temperature as it goes up, but its reaction time lags temperature in a smeared response some 800 years long. So as temperature sharply reverses and reaches a low 800 years through the 1500 years of the YDS, the CO2 stays flat for the whole 1500 years.

So: pretty evident that CO2 follows temperature.

[agere_contra]

I forgot to mention: The Younger Dryas temperature change was not completely global: in particular Antarctica would have missed it.

But the CO2 change WAS global thanks to excellent mixing. So a CO2 signal from ice from Antarctica shouldn’t be uncritically compared against an Antarctica temperature proxy. Compare the CO2 behaviour against as many global temperature proxies as possible.

[agere_contra]

Lastly: WattsUp references this key paper which gives an excellent breakdown of the Global temperature proxies used.

It's obvious that there are a wealth of global temp proxies in a cloud around the CO2 results. The Shakun authors must have used an industrial cherry-picking machine to find the proxies that suited their purpose.